Materials

Question 1

Density

Answer 1

Mass per unit of volume of a material

Question 2

Volume of a regular solid: Cuboid, Sphere and Cylinder

Answer 2

Cuboid - length x width x height
Sphere - 4/3 x pi x r^3
Cylinder - pi x r^2 x h

Question 3

Volume of irregular solid

Answer 3

Fill up a eureka can up with water and place the regular solid in it
Measure the volume of displaced water in a measuring cylinder
Volume of water displaced = volume of solid

Question 4

Hooke’s Law

Answer 4

Extension of a spring is directly proportional to the force applied, up to the limit of proportionality

Force applied (N) = spring constant (Nm) x extension (m)

Question 5

Spring Constant (k)

Answer 5

Force applied per unit extension

Question 6

Higher spring constant means?

Answer 6

The stiffer the material

Question 7

Effective spring constant of springs in parallel?

Answer 7

Ke = K1 + K2 + …

Question 8

Effective spring constant of springs in series?

Answer 8

1/KE = 1/k1 + 1/K2 + …

Question 9

Limit of proportionality

Answer 9

The force is proportional to the extension

Question 10

Elastic deformation

Answer 10

Material returns to its original length when the force is removed

Question 11

Plastic behaviour

Answer 11

Permanent deformation

Question 12

Hysteresis

Answer 12

Loss of energy as heat
Equal to the are between loading and unloading curves

Question 13

Thermal energy lost as heat equals?

Answer 13

Area underneath the loading graph, minus area underneath the unloading graph

Question 14

Elastic strain energy is …

Answer 14

Energy stored in a spring when stretched

Question 15

Elastic strain energy (J) =

Answer 15

1/2 x F(N) x Extension (m)

Question 16

Elastic strain energy is also equal to?

Answer 16

Work done to a stretched wire

Question 17

Area underneath Force(N) and extension (m) graph is equal to?

Answer 17

Elastic potential energy

Question 18

Stress

Answer 18

Force per unit cross-sectional area
Tensile stress (Pa) = Force (N)/ Area (m^2)

Question 19

Strain

Answer 19

Extension of a material per unit original length
Tensile strain = Extension (m)/ original length(m)
No units –> Ratio of two lengths

Question 20

Young’s Modulus

Answer 20

Young’s Modulus E (Pa) = Tensile stress/ Tensile strain

Question 21

Equation for Young’s Modulus

Answer 21

E = Force x length/ Area x change in length

Question 22

Brittle

Answer 22

Material snaps with no noticeable yield

Breaks soon after reaching its elastic limit

Question 23

Ductile

Answer 23

Material exhibits plastic behaviour

Breaks long after elastic limit on strain axis

Question 24

Strong

Answer 24

Little strain for high stress

Steep gradient on stress-strain graph (High YM)

Question 25

Weak

Answer 25

Large strain for little stress

Shallower gradient on stress-strain graph (Low YM)

Question 26

Hard

Answer 26

High ultimate tensile stress

Breaks under high stress

Question 27

Tough

Answer 27

Large amount of energy a material can absorb before it breaks

Large area under the stress-strain graph before material breaks